SAN FRANCISCO — An Oakland man was arrested by San Francisco police Saturday on suspicion of criminal threats and stalking, the day after a North Oakland elementary school was locked down when a student’s family received threatening notes from an acquaintance, authorities said.

Matthew Eisenhower, 45, was taken into custody at San Francisco’s central police station and was being held Saturday afternoon on $1 million bail, said police Officer Albie Esparza.

On Friday, the Oakland Unified School District secured a stay-away order for Eisenhower, and access to Peralta Elementary School was restricted all day, with extra security and police presence, said school district spokesman Troy Flint.

The move came after the family of a student received threatening notes from someone they knew, with one note mentioning that the person had information about where their child attended school, Flint said. He said Oakland police worked with San Francisco police on the stay-away order but declined to give further details.

In a video clip recorded by a student, a psychology instructor at Orange Coast College told her class that the election of Donald Trump was “an act of terrorism” – prompting an official complaint from the school’s Republican Club.